This invention relates to razors, and is particularly concerned with a safety razor of the kind comprising a handle and a blade unit mounted on the handle with the capability to pivot during shaving to adjust itself to the contours of the surface being shaved, there being spring means acting between the handle and blade unit to urge the blade unit to a xe2x80x9crestxe2x80x9d position.
In known razors of this kind the pivot axis, as seen in a direction perpendicular to a plane containing the guard surface and the edge of the blade adjacent to the guard, is located between the guard and the cap of the blade unit, i.e. generally behind the blade or blades, and the blade unit is arranged to pivot in both directions from its rest position. With such arrangements the handle tends to impede flow of water through the blade unit for rinsing away soap and shaving debris.
In accordance with the present invention there is provided a safety razor comprising a blade unit including a guard and at least one blade, and a handle mounting the blade unit for pivotal movement in one direction only from a rest position, characterised in that the pivot axis underlies the guard surface as seen in a direction normal to a plane containing the guard surface and the edge of the adjacent blade.
With the pivot axis located to underly the guard surface, the force of the blades against the skin during shaving will be mainly influenced by the spring means which opposes pivotal displacement of the blade unit from the rest position and applies a restoring force to return the blade unit to the rest position when it has been deflected from that position. As a consequence if the user wishes to apply more force to the guard, for example to stretch the skin, this can be done without increasing the force of the blades on the skin. This could not be achieved by prior art razors.
In addition, the handle can be arranged so as not to obstruct flow or rinsing water through the blade unit and in accordance with a preferred feature, with the blade unit in he rest position, the handle is located entirely forwardly of a plane containing the edge of the blade adjacent the guard and perpendicular to said plane containing said edge and the guard surface. (For convenience the latter plane is hereinafter referred to as the xe2x80x9ctop planexe2x80x9d of the blade unit.) Ideally the handle is located entirely forwardly of a plane containing the trailing edge of the guard surface and perpendicular to the top plane of the blade unit.
The blade unit may be pivotally movable through an angle in the range of 35xc2x0 to 50xc2x0, preferably 40xc2x0 to 45xc2x0, from the rest position to a limit position, and both these end positions are conveniently defined by stops provided or on the blade unit for abutment by the handle connection pieces.
In a specific embodiment of the invention, when the blade unit is in the rest position, the top plane thereof is at 20xc2x0-30xc2x0 to the longitudinal axis of the handle, i.e. the axis of that part of the handle intended to be held in the hand. Furthermore, the pivot axis is 1.0-2.0 mm, preferably 1.25-1.7 mm, from the leading blade edge and 0.50-1.00 mm below the guard surface.
In accordance with a second aspect the invention provides a razor comprising a blade unit, and a handle mounting the blade for pivotal movement, from a rest position, the handle being connected to the blade unit by a pair of opposed connection pieces engaging the blade unit at the respective ends thereof, characterised in that the connecting pieces are urged resiliently into abutment with cam faces on the blade unit whereby to oppose displacement of the blade unit from the rest position and to apply a restoring force for returning the blade unit to the rest position after having been pivoted away therefrom.
Conveniently the handle has a pair of wings with tips forming the connection pieces and biased apart by the wings. In one embodiment, the handle is intended to be used with blade units in the form of replaceable cartridges, and the wings are hinged elements acted upon by spring means incorporated in the handle structure. In another embodiment the wings are integral with the handle and are themselves resilient. In both cases the wing tips comprise pivot elements, particularly pins or stub axles, which cooperate with complementary means on the blade unit to define the pivotal connection between the handle and blade unit. Adjacent their pivot elements, the wing tips have edge surfaces which abut the cam faces. It will be appreciated that by virtue of the wing tips a simple pivot assembly with return spring is obtained. Furthermore, the blade unit can be made easily detachable by squeezing the wings together.